Making oxygen concentrators portable has been an old and long standing problem in this art. There have been sold, and continue to be sold, converters which will convert DC as is available in automobiles and other vehicles, to AC so that a unit designed for the home could also be used in the car. The problems with this are that the unit was relatively large, it tended to fall over, and the adapter system drained excessive energy from the car's electrical system. In addition, such adapters were relatively expensive and required additional expense and effort to install into the car. Thus, an object of the invention is to avoid the need for such DC to AC adapter systems, also known as inverters.
The prior art includes soe machines designed for DC operation. The problems here include that such machines tended to be of a high profile so that they were unstable in moving vehicles, and, in addition, power consumption was still a problem. Such machines were designed to be plugged into the automobile cigarette lighter socket. However, in addition to the power consumption problem, this time it includes a dangerous fire hazard. Because the amperage required by such DC oxygen concentrators was greater than the design maximum of the cigarette lighter's socket, there was a severe danger of a fire in the automobile's wiring.
Yet another problem in the prior art concerning the use of such AC to DC inverters and DC machines is that many patients require relatively high flows of oxygen. That is, the sicker the patient the more oxygen he or she requires, and thus the harder the machine must work to provide the increased oxygen. This tendency among patients to require more oxygen further aggravates the already severe power consumption problem in such prior art devices.
An approach in the prior art which also failed was to simply put a DC compressor in an otherwise existing AC machine. This turned out to be not workable because oxygen concentrators designed for home or stationary use usually have vertical beds. For a portable unit for use in vehicles, the unit must have a low profile and a low center of gravity in order to not be upset during normal motion of the vehicle. Further, on airplanes the unit must have a low profile in order to fit under an airplane seat. In automobiles, the unit must fit in the foot well of the vehicle, often in the back seat. The unit must be able to be used with all sizes of automobiles including the smaller automobiles. Thus, simply putting a DC compressor in an existing home unit did not work because the unit was unstable and because it would not fit into the vehicle in the manner required, as set forth above.
Providing portable oxygen for respiratory patients has been attempted using many forms of stored oxygen. All such schemes that depend upon storing oxygen have inherent disadvantages which are overcome by concentrators inherently.
In aircraft, bottles of oxygen are potential explosion hazards and thus are to be avoided. In fact, many airlines refuse to allow such pressurized cylinders of oxygen or any other gas on-board.
Airlines are accustomed to working with chlorate candles of various sorts. However, these schemes are undesirable because they involve ignition and burning, processes highly undesirable on aircraft, and also undesirable in automobiles. Further, chlorate candles are relatively expensive and produce a great deal of heat. In general, they are a very dangerous way to store oxygen.
Summarizing, any system that depends upon the storage of oxygen inherently has problems. If the oxygen is stored chemically, getting it out of its chemical "lock" usually produces heat and other undesirable side effects. If the oxygen is stored as a gas under pressure, pressurized vessels are dangerous and undesirable for transport in any sort of vehicle. Further, stored oxygen upsets the air balance inside the vehicle, and this is especially important when considering pressurized aircraft flying at high altitudes. Oxygen concentrators do not change the balance or mixture of the air. That last statement is true, even though it may not seem logical at first. Tests have proved that oxygen concentrators do not upset the air balance or air mixture in the space in which they are used.
The invention achieves its low profile using a unique combination of features, one of which is to position the beds in a horizontal orientation. The PSA art has long known that horizontal beds are susceptible to channeling of gas through the bed, which in turn permits fluidization of the sieve material followed by rapid destruction of the molecular sieve material in the bed.
While spring loaded beds have been used in other environments, they are new in this environment of a low profile portable PSA unit. The spring loaded bed keeps the sieve tightly packed even as it normally breaks down slightly in use. Further, improved means to achieve this end are also provided.
The prior art, in general, has not had a fully acceptable portable medical oxygen concentrator. The present invention fills that need with an efficient machine which is durable and well suited to the rigors of portability and use in vehicles of all sorts.